Ebola crisis: How will Liberia's vaccine trial work?

Volunteers in Liberia are being injected with a tiny quantity of Ebola in the first ever large scale vaccine trials against the deadly virus.

The trials will eventually involve almost 30,000 volunteers in the country, where nearly 4000 people have already died from Ebola.

Scientists hope that by introducing a small quantity of the virus, volunteers' bodies will be 'tricked' into fighting the disease.

Dr Stephen Kennedy, the senior Liberian scientist involved, explained to the BBC's Mark Doyle how it will work.